VB6 Notes

Unicode String handling in VB6

VB6 `String` variables can handle web data received in UTF-8 encoding, but with some limitations and potential issues.

Since VB6 uses Unicode (UCS-2) internally to represent strings, it can handle Unicode characters. However, there are a few things to consider:

1. UTF-8 to UCS-2 conversion: When receiving UTF-8 encoded data from the web, VB6 will automatically convert it to UCS-2 (the internal Unicode encoding used by VB6). This conversion is done by the `MSXML2` library, which is used by VB6 for XML and HTTP parsing.
 
2. Byte order: VB6 uses little-endian byte order for Unicode characters, which is the same as the byte order used by Windows. However, if the received UTF-8 data is not properly converted to UCS-2, you may encounter issues with byte order.
 
3. Non-ASCII characters: VB6 can handle non-ASCII characters, but it may not display them correctly if the system's default code page is not set to a Unicode-aware code page.
 
4. Malformed UTF-8 data: If the received UTF-8 data is malformed or contains invalid characters, VB6 may not be able to handle it correctly.

In general, VB6 `String` variables can handle web data received in UTF-8 encoding without explicit conversion, but you should be aware of the following potential issues:

• Implicit conversion: VB6 will automatically convert the received UTF-8 data to UCS-2, which may lead to issues if the conversion is not done correctly.
• Character encoding: VB6 may assume the wrong character encoding if the received data is not properly marked with a byte order mark (BOM) or if the system's default code page is not set correctly.
• Data corruption: If the received UTF-8 data is malformed or contains invalid characters, VB6 may not be able to handle it correctly, leading to data corruption or errors.

To minimize potential issues, you can take the following precautions:

• Use the `MSXML2` library: Use the `MSXML2` library to parse XML and HTTP data, as it provides built-in support for UTF-8 encoding and Unicode characters.
• Specify the encoding: When sending or receiving data, specify the encoding explicitly (e.g., `charset=utf-8`) to ensure that both parties agree on the encoding.
• Check for BOM: Check for the presence of a BOM (byte order mark) in the received data to determine the encoding.
• Use Unicode-aware APIs: Use Unicode-aware APIs, such as the `WideCharToMultiByte` function, to convert between Unicode and non-Unicode encodings.